A New Pulse Delta-Sigma CO2 NDIR Gas Detector

This work describes the implementation and the modeling of an infrared gas sensor with pulse delta-sigma sensing architecture. Beyond the conventional technique of constant periodic heating of infrared light source, our proposed delta-sigma architecture with closed-loop feedback system is built with the hybrid combination of a CO2 infrared sensor with a specific wavelength filter, an infrared MEMS heater, a chopper amplifier, threshold comparator, ARM based MPU and discrete electronic devices. After a modeling of system, we built a model for the description of relationship between gas concentration and sensor by the duty of heating. The measurement results show a good linear behavior of signal and it proves to be a practical for all the NDIR measuring techniques and this work also gives a new approach not only to measure gas concentration fast but also obtain the high resolution.